This invention relates in general to heat exchange equipment and more particularly to cooling towers.
Steam turbine generating equipment accounts for much of the electrical energy produced in the United States, and as any heat engine, a steam turbine cannot convert all of the heat energy that is supplied to it in the form of steam into mechanical energy. Much of the energy which is not converted is lost condensing the low pressure steam that leaves the turbine back into water, and this normally occurs at a water-cooled heat exchanger, more commonly known as a condenser.
Heretofore, it was common practice to locate generating installations adjacent to large bodies of water such as lakes and rivers, for these bodies provide convenient sources of cooling water for the condensers. Indeed, the water was merely pumped out of the lake or river, circulated through the condensers, and then returned to the lake or river at an elevated temperature. Concern for the environment has to a large measure curtailed this practice.
Most generating installations of recent design discharge the waste heat ultimately to the atmosphere instead of to a river or lake, this transfer taking place through intermediate units commonly referred to as cooling towers. The typical cooling tower for a utility plant has a stack that is often over 300 feet high and a circular cooling section that surrounds the base of the stack. The cooling section in turn has a distribution basin located at an elevation of perhaps 50 feet, it being supported on a series of columns. The base of the stack has large openings which open into the region under the distribution basin, and as a consequence, air passes beneath the distribution basin and then rises through the stack to be discharged into the atmosphere at the upper end of the stack. The elevated basin receives hot water from the condensers and discharges this water through a multiplicity of downwardly directed apertures or nozzles. Directly beneath the distribution basin at grade elevation is a collecting basin which collects the water discharged from the nozzles. As the water descends, it passes through the air stream and hence loses some of its heat to the air stream.
To enhance the transfer of heat between the water and air, a multitude of baffles or fill slats are interposed between the two basins such that the water will not flow in well defined streams from the various nozzles, but instead will be dispered into finely divided cascades or splashes. The slats, which are collectively referred to as fill, are nothing more than wood or polymer strips that extend through openings in wire grids and hence are supported on the grids. The grids are spaced relatively close together so that a single slat will pass through several of them, and each grid extends substantially the entire height between the two basins, it normally being suspended from anchors embedded in the underside of the distribution basin.
Conventional cooling towers of the foregoing arrangement proved quite satisfactory at the outset, but in time began to deteriorate, particularly in the northern climates where the water can freeze. In this regard, the weight of the fill is substantial and in time is enough to pull the anchors loose from the bottom of the distribution basin. The formation of ice in the fill compounds the problem, because it increases the weight of the fill significantly. Indeed, at some installations, the weight has been great enough to cause a partial collapse of the distribution basin. In short, cooling towers of current construction are not durable and require constant maintenance, even though they are formed largely from materials, such as concrete, that are considered maintenance free.
Others have supported the fill on wooden frameworks which are in turn supported at the bottoms of the cooling sections, but a framework of this type is complex and expensive to construct. This derives from the fact that it constitutes a multitude of pie-shaped sections in order to accommodate the curvature of the circular cooling section.